Centrifugal fan.



No. 762.470. PATENTED JUNE 14, 1904.

s. o. DAVIDSON. GBNTRIFUGAL PAN.

APPLICATION FILED APB. 11 1903. N0 MODEL. 2 SHEETS-SHEET 1.

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PATENTED JUNE-1'4, 1904.

s; c; DAVIDSON. OENTRIFUGAL FAN.

APPLIUATION FILED APR. 11. 1903.

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INVENTORI By his Attorneys,

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Patented June 14, 1904.

UNITED STATES PATENT ()EEicE.

SAMUEL CLELAND DAVIDSON, OF BELFAST, IRELAND.

CENTRI'FUGAL FAN.

SPECIFICATION forming part of Letters Patent No. 762,470, dated June 14,1904.

Application filed April 11, 1903. Serial No, 152,144. (No model.)

To (til 10,7107 it may concern:

Be it known that I, SAMUEL CLELAND DA- VIDSON, merchant, of SiroccoEngineering I/Vorks, Belfast, Ireland, have invented certain new anduseful Improvements in Centrifugal Fans, of which the following is aspecification.

My improvements relate more particularly to centrifugal fans whenemployed for the removal of shavings, straw, rags, and other substancesof a stringy nature (hereinafter called the material) from workshops bydrawing same first through suction pipes or ducts connected to theinlet-opening to the fan, thence through the fan itself, and thenpropelling same from the fan discharge-nozzle through a pipe to whereverthe material may require to be delivered.

My invention provides also a new fan specially adapted for conveying bya blast of air and through the fan a great variety of materialssuch, forexample, as are now handled by pneumatic stackers and the like.

In the ordinary construction of said centrifugal fans the inflowingcurrent of air in which the material is carried (hereinafter called theair-current) is admitted to a space within the inner edges of the bladesconstituting an intake-chamber within the fan itself which ispractically a continuation of the inlet-opening in the fan-casing and ofsubstantially equal diameter therewith, and in some forms of said fansthe lateral ends of the blades are connected together and sometimesentirely closed by a ring or annulus. A serious difiiculty hithertopertaining to the employment of such fans for duty of the abovedescribednature is that stringy substancessuch as shavings, straw, rags, &c.-onentering the fan get, as it were, astride of the inner edges of thefan-blades, so that the fan itself soon becomes completely choked uptherewith, thus necessitating its being frequently stopped to be cleanedout; and the object of my improvements is to so construct the fan thatit is impossible for the material passing through it to effect anylodgment on the edge of the blades.

According to this invention the edges of the fan-blades which face theinlet are so formed and their axial edges so assembled that no edges areexposed which will overhang or obstruct the path which the material willtravel through the fan-from inlet to discharge, for instance. I entirelyclose the inner edges of the blades throughout their entire length bymounting and attaching same upon a central cylindrical hub or by fittingthem with a central shield, so that said inner edges of the blades arethus entirely sheltered from material lodging upon or passing throughbetween them, while the lateral ends of the blades toward theinlet-openings of the fan are left ontirely open and unconnected withone another and have no projection axially beyond the terminal end ofthe inner edges of the blades toward the inlet-opening but preferablyare in the same plane or recede therefrom in the direction of the centerof the tips of the blades. By this means no surfaces are exposed uponwhich the material can lodge or be retained by centrifugal tendencyunder the action of the fan. The inlet-opening to said fan I preferablymake of a diameter at least as great as, and preferably substantiallygreater than, that of the circle in which the inner edges of the bladesrotate, and which inlet-opening communicates directly with the spacesbetween the blades through between the lateral ends thereof, and asthere is absolutely no radial flow of air from the center of the fanthrough between the inner edges of the blades the entire flow of airtakes place axially over and past the lateral edges of said blades intothe spaces between same. The size of the inlet-opening facilitates alsothe assembling of the fan in the casing.

In my preferred construction or form of the fan I make the lateral edgesof the blades toward thev inlet-opening into the fan-casingsubstantially radial from the fan-shaft or with a slight taper towardthe center of their tip edges, so that any material which may getastride of said lateral edges when entering the fan through theinlet-opening in the fancasing will slide along said lateral edges up toand be thrown off the tips of the fan-blades by centrifugal force thatis to say, the inner ends of said lateral edges extend toward thefan-inlet at least as far as, and preferably beyond, the outer endsthcreof and, further,

in order that this material when it comes through the fan-inlets inlumps or clusters, as is frequently the case with rags or shavings (anarmful of which at a time is often thrown into the suction-pipes leadingup to the faninlet) or with blocks of wood which may accompany theshavings and which are too large to enter the space between the blades,and consequently only strike against their lateral edges, maynevertheless pass with the air-current through the fan without jammingbetween the blades and the sides of the fan-casing facing same, I makethe axial width of the fan-casing sufiiciently larger than the greatestaxial width of the blades to provide a passageway for said material topass from the inlet-v opening to the circumference of the fan-casingwithout having to enter the spaces between the blades. In practice Ihave found that the provision of this space does not to any materialextent detract from either the suction or discharge pressure of the fan.

By tapering the blade edges as described the tip edges will be shorterthan their inner edges, while the radial edges of the blades form anobtuse angle with the axial direction of the inflowing air through theeye of the fan-casing to the "blades, said radial edges being entirelyopen and unconnected with one another, except at the hub, and with thecorner between said radial and the tip edges of the blades preferablyrounded to let any material which may get astride of the radial edges bethrown off same more freely.

The intermediate surface of the blades between their inner and tip edgesmay be formed as a plane, but are preferably with a concave curve in thedirection of the fans rotation, through a line parallel with the axis ofthe fan, whereby not only is the strength of the blade greatly enhanced,(which is a very important matter for duty of this class when the fansare running at a high speed, as the edges of the blades then strikeagainst the material with much force,) but the action of the blades onthe air is also improved as compared with what same would be if theblades were made with a flat surface between said radial edges thereof.

Reference to the accompanying drawings will more fully explain thenature of my invention and how same is carried into effect.

Figure l is a cross-sectional elevation; Fig. 2, a side elevationlooking in the direction of the inlet to the fan, and Fig. 3 a plan ofthe wheel or rotary member of one form of my improved fan for thepurpose described. In the latter view for clearness of reference onlythree blades are indicated.

The letters indicating the various parts are the same in each figure andare as follows:

a is a disk to which is attached a central hollow cylindrical hub 7),the opposite end of which from the disk is closed by preferably acone-shaped projection c, the apex of which is toward theinlet-openingof the fan. Around the outersurface of said hubb the inner edges of theblades (Z (Z are mounted as close-fitting attachments and without anyaxial projection beyond the end of said cylindrical hub. The radialedges of said blades which are next the disk are suitably flanged forattachment thereto, and the opposite radial edges, which are toward theinlet-opening in the fan-casing, are preferably made with a slight taperfrom the hub outward toward the tips in the direction of the fan-disk,as shown at e 0, so. that their tip edges 9 g are shorter than theirinner edges ff, and said radial edges 0 e and tip edges 0 r are openfrom disk to hub and without any intermediate connections from one bladeto the other. The inner axial edges f are also flanged, as shown, so asto stiffen the curve by forming a sort of diaphragm across it to make astrong attachment and at the same time leave free the spaces between theblades. When the blades are thus constructed, the centrifugal forcedeveloped when the fan is rotating causes any string like material whichthe inflowing air may drive against and place astride of the radialedges of the blades to slide along same to and be thrown clear off thetips, and as the material has thus no catchment-place of any sort on theedges of the blades and as there is sufficient space provided at betweenthe open radial edges and the side of the fan-casing facing same for anymaterial which gets astride of the radial edges of the blades to passfreely between same and the side of the easing without jamming, whilethe surfaces of the blades and of the disk have no projections of anysort upon which the material passing through into the spaces between theblades could effect a lodgment, the air current 7 through the fanconsequently carries the material along with it at substantially its ownvelocity and discharges it through the dischargenozzle from thefan-casing. The corner between said radial and tip edges of the bladesis preferably rounded, as shown at h it h, to let any of the materialwhich may get astride of the radial edges be thrown off same morefreely.

The above-described operation of my improved fan is so effective thatafter a long period of work in discharging through it stringyn1aterialsuch as long shavings, cotton-waste, ribbon-like rags, orcuttings of leather, &c.-the blades are found to be clean and free fromany lodgment of such material upon them.

Z; is an annular ring forming the inlet-opening to the fan and ofgreater diameter than the fan itself, to the inner side of which isfitted an inwardly-tapering ring Z, which at its inner end is preferablyof slightly less diameter than that of the circle in which the tip edgesof the blades revolve.

m is the fan-casing; w, the inlet-opening therein, within which the rink7:: and its contained cone-ring Z are detachably applied, so that onremoval of these the rotary member of the fan can be inserted orwithdrawn bodily through the inlet-opening w in the side of the casing.

0 is the pedestal on which the bearings 19 p for driving shaft q aremounted, the latter being driven by the pulley r.

I do not limit myself to the particular construction and arrangement ofthe fan or fanblades shown in these drawings, as it will be obvious thatthe fan itself may be constructed with an inlet on both sides and thatthe blades may be attached to said hub only without employment of anydisk; but in my preferred construction of double-inlet fan I usuallyemploy a disk with blades mounted on each side thereof, so that the twooppositely-entering currents of air are kept separate until theirdischarge from the periphery of the fan.

What I claim, and desire to secure by Letters Patent, is

1. A centrifugal fan for the removal of shavings, straw, rags and othersubstances of a stringy nature, comprising the combination of ablade-carrying part, blades disposed radially of the axis with a lateraledge facing the air-inlet to the fan, the inner ends of said lateraledges extending toward the inlet beyond the outer ends thereof, therebyinsuring that any material striking the blade edges will by itscentrifugal tendency slide along the same and be duly delivered from thetips of the blades, substantially as and for the purpose set forth.

2. In a centrifugal fan for the removal of shavings, straw, rags andother substances of a stringy nature, the combination of a central hubmounted on the fan -shaft, fan-blades mounted upon said central hub, adisk disposed at right angles to and connected with said hub, means forattaching said blades to the disk whereby the blades are supported onthat side as well as from the hub, the radial edges nearest the inletbeing entirely open and unconnectcd with one another except at the huband having their inner ends extending toward the inlet beyond theirouter ends to insure that material striking the blade edges will by itscentrifugal tendency slide along the sameand be duly delivered from thetips of the blades, substantially as and for the purpose set forth.

3. In a centrifugal fan for the removal of shavings, straw, rags andother substances of a stringy nature, the combination of a central hub,radial fan-blades mounted with the entire length of their inner axialedges upon said hub, the lateral edges of said blades facing thefan-inlet being entirely open and unconnected with one another except atthe hub, an inelosing casing for saidfan-blades, the parts beingarranged to provide a space between said lateral edges of the blade andthe side of the inelosing casing of the fan facing same, and said spacebeing of sufficient dimensions to provide a passage-way by which thematerial may pass through the fan with out of necessity entering betweenthe blades, substantially as and for the purpose set forth.

4. In a centrifugal fan for the removal of shavings, straw, rags andother substances of a stringy nature,the combination of fan-bladesmounted with the entire length of their inner axial edges as a closeattachment upon a central cylindrical hub carried upon the shaft of thefan, the plane in which the radial edges of the blades rotate being, onthe inlet side, inclined away from the axis toward the tip edges of theblades so that such plane forms an obtuse angle with the axial directionof the inflowing air through the eye of the fan-casing to the blades,said radial edges being en tirely open and unconnected with one anotherexcept at the hub, and an inelosing casing for said fan-blades, saidcasing and fan arranged to form a free space between said radial edgesof the blades on the inlet side and the side of the inelosing casing ofthe fan facing same, substantially as set forth.

5. In a centrifugal fan for the removal of shavings, straw, rags andother substances of a stringy nature, the combination of a centralcylindrical hub mounted on the fan-shaft, fanblades mounted with theentire length of their inner axial edges as a close attachment upon saidcentral cylindrical hub, a "disk disposed at right angles to andconnected with said hub,

flanges on the radial edges of the blades which are farthest from theair-inlet, mcans'for attaching said flanges to the disk whereby theblades are supported on that side as well as from the hub while the,other opposite radial edges of said blades are entirely open andunconnected with one another except at the hub, the said edges of theblades being inclined away from the inlet toward the tip edges so thatsuch edges form an obtuse angle with the axial direction of theinflowing air from the eye of the fan-casing to the blades, and aninclosing casingfor said fan, said casing and fan arranged to form afree space between said radial edges of the blades and the side of theinelosing casing of the fan facing same, substantially as set forth.

6. In a centrifugal fan for the removal of shavings, straw, rags andother substances of a stringy nature, a fan-shaft, fan-blades disposedradially of the axis with a lateral edge facing the inlet which isaxial, the inner ends of said lateral edges extending toward the inletbeyond the outer ends thereof, and a hub on said shaft for receiving andholding said blades, the end of the hub which faces the inlet having itsedge approximately flush with the edges of the fan-blades on that side,substantially as and for the purpose set forth.

7. In a centrifugal fan for the removal of shavings, straw, rags andother substances of a stringy nature, the combination of a fanshaft,fan-blades disposed radially of the axis with one lateral edge facingthe inlet which is axial, the inner ends of said lateral edges extendingtoward the inlet beyond the outer ends thereof, a hub on said shaft forreceiving and holding said blades, the end of said hub which faces theinlet being free and eoned with its base approximately flush with theedges of the fan-blades on that side and its apex projeetii'ig beyondsaid blade edges, substantially as and for the purpose set forth.

8. In a centrifugal fan for the removal of shavings, straw, rags andother substances of a stringy nature, the combination of a shaft, a hubon said shaft, concave radial blades fixed to said hub and formed with alateral edge facing the air-inlet and the concavity facing

